I don't see any rules about how far the rear wing or brackets (uprights) can stick behind the car. I am looking at one of those rear bumper/crash bar mounted wings for my 350z, the brackets/uprights. stick maybe 6 inches behind the car.

2) ST4 Specific Aerodynamic Modification Allowances (if not using OEM Mod Factor):Aerodynamic parts/devices/aides shall be limited in ST4 to the following:a) All of the items listed above in section 7.3.2.D.1) “OEM Aero” Modification Factor.b) Vertical front air dam (5º tolerance) that follows the outermost edge of the front andside bodywork/fascia.c) Single flat, horizontal front splitter that protrudes no greater than 4” from the vehicle.d) Single rear wing or spoiler that does not exceed a height of 8” above the roof line,or width greater than the vehicle’s body width, or end plates greater than 12”.e) Modified BTM, non-Base Trim Model (non-BTM), or replaced front fascia (unlessspecifically approved in Appendix B:i) May have nothing attached to it other than specifically allowed items (above).ii) May not have canards/winglets molded into it.iii) Any item that is molded into the fascia that functions as an airfoil, deflector, dive plane, or vortex generator and extends 2" or more past the outline of theimmediate surrounding fascia is prohibited. To inspect: a plumb line run acrossthe entire surface of the fascia and bumper shall not have any such item thatextends 2” past the line when viewed from above.f) Cutting/removal of the rear bumper cover/fascia where it does not cover the rearframe/bumper cross beam.

Part d mentions the rear wing max height, width, and endplate info, and part f mentions the rear bumper cover/fascia, but I didn't spot the exact info you're looking for. Part c restricts how much the splitter can extend, but I didn't spot anything about how far back the wing can be.

d) Single rear wing or spoiler that does not exceed a height of 8” above the roof line

means any part of the wing (wing elements and end plates) can't exceed 8" above the roof, or does it just mean the wing elements and not the end plates? Thanks!! - Jim

I've always built wings so that the wing element is below the height limit, for multiple organizations. Never had anyone bring up endplate height. We usually leave a little wiggle room - about half an inch from the top at the max Angle of Attack of the wing.

Max AoA is 12° on this AJ Hartman Aero carbon wing, but we run it closer to 6° so we're even further away from the height limit.

Don't let the wide angle image fool you - its legal width, too. Wing can be "as wide as the car" but measuring the car's width is also tricky. The widest part of this E46 Coupe was at the rear fenders, as you cannot count the mirrors. I also assumed we couldn't count the TT4 legal flares we added - so we measured another identical E46 coupe using two levels at the fenders and a tape between, above the car. Then we went 1/2" narrower for the wing element, again for some wiggle room and to account for measurement error.

On the last lap of the last session of the last event of the year I clipped a tire wall and popped the driver's side mirror off! Luckily the wing and even the bolt-on flares were narrower than the mirror, so no other damage was done. It would have sucked to rip the wing off on that "overzealous corner exit".

Gave us a good opportunity to make the car better, by removing the heavy "barn door" side mirrors and replacing them with smaller, lighter, and sleeker "E36 M3 style" mirrors. $34 on eBay, scary, but they work fine - just lost the power control.

Now we ran only ran TT4 once, at 635 pounds overweight (or 95 whp underpowered) at the end of the 2017 season (this was really a TTD car for 2 years, then we added aero). If we will ever see the TT5 numbers we might jump down to there, but the rules are supposedly going to be "unique to TT5/TT6" so I suspect they will neuter the aero limits worse than even ST4/TT4...

d) Single rear wing or spoiler that does not exceed a height of 8” above the roof line

means any part of the wing (wing elements and end plates) can't exceed 8" above the roof, or does it just mean the wing elements and not the end plates? Thanks!! - Jim

I've always built wings so that the wing element is below the height limit, for multiple organizations. Never had anyone bring up endplate height. We usually leave a little wiggle room - about half an inch from the top at the max Angle of Attack of the wing.

Max AoA is 12° on this AJ Hartman Aero carbon wing, but we run it closer to 6° so we're even further away from the height limit.

Don't let the wide angle image fool you - its legal width, too. Wing can be "as wide as the car" but measuring the car's width is also tricky. The widest part of this E46 Coupe was at the rear fenders, as you cannot count the mirrors. I also assumed we couldn't count the TT4 legal flares we added - so we measured another identical E46 coupe using two levels at the fenders and a tape between, above the car. Then we went 1/2" narrower for the wing element, again for some wiggle room and to account for measurement error.

On the last lap of the last session of the last event of the year I clipped a tire wall and popped the driver's side mirror off! Luckily the wing and even the bolt-on flares were narrower than the mirror, so no other damage was done. It would have sucked to rip the wing off on that "overzealous corner exit".

Gave us a good opportunity to make the car better, by removing the heavy "barn door" side mirrors and replacing them with smaller, lighter, and sleeker "E36 M3 style" mirrors. $34 on eBay, scary, but they work fine - just lost the power control.

Now we ran only ran TT4 once, at 635 pounds overweight (or 95 whp underpowered) at the end of the 2017 season (this was really a TTD car for 2 years, then we added aero). If we will ever see the TT5 numbers we might jump down to there, but the rules are supposedly going to be "unique to TT5/TT6" so I suspect they will neuter the aero limits worse than even ST4/TT4...

Cheers,

If you were that far away from TT4 power to weight limits... had you done too many other little things to stay in TTC?

Also, as I have a minimally prepared... (but class limit TTD E36M3)... I really hope I don't find myself classed in TT5 gridding up next to your beautifully built monster in 2018.

If you were that far away from TT4 power to weight limits... had you done too many other little things to stay in TTC?

Well this was really a TTD car that we ran for the past two seasons...

Was getting ready for a jump to TT4 for 2018, so we did the (then legal) ST4/TT4) max aero mods and just ran it in TT4 "heavy" at our last NASA event of 2017. I knew TTC was going away so we didn't bother running there for this one event.

MemphisRob wrote:

Also, as I have a minimally prepared... (but class limit TTD E36M3)... I really hope I don't find myself classed in TT5 gridding up next to your beautifully built monster in 2018.

Looks like the TT5 rules just dropped - and they are worse than we thought. I would have to add a LOT of weight to this car go from TTD to TT5, so that's out for me. TTD was already slow enough... sheesh.

And with the "only a year old and already changed" ST4/TT4 aero rules re-write (above) that dropped yesterday, now this car isn't legal for ST4/TT4 anymore. Oh well, was legal for ONE event!

It seems like someone either doesn't know how to write rules well enough to miss giant omissions or obvious loopholes, or they see something that a racer thought of and they want to punish the early adopters. Either way it sure seems to happen a lot to me. "What is the saying, you're not paranoid if its true?"

Back to the drawing board... now I get to spend thousands more to chase the ever moving ruleset. Damn I left the SCCA for this nonsense, years ago.

I feel your pain, and I haven't even completed my Pro-Challenge Mustang yet.

I read the rules last year and started prepping it for ST4. I emailed the ST director for clarification on the rear wing, re: whether the rules meant I was restricted to a "single element" wing, or if a single wing with dual elements was legal.I got a very short response, basically insulting my intelligence for even asking the question. SMH.

Now I look at the new rules, and the car could be setup for ST4 or ST5, but with "No additional aero mods".Does this mean I cannot run ANY wing or air dam at all, or is the wing and air dam supplied from Pro-Challenge on their standard roadrace car legal?

It would be nice to think I could buy all these expensive parts once, and run the car for many years, without chasing an ever-changing rule set from one year to the next. I just want to have some fun in my retirement, without blowing my whole nest-egg in the first 5 seasons..

I feel your pain, and I haven't even completed my Pro-Challenge Mustang yet.

I read the rules last year and started prepping it for ST4. I emailed the ST director for clarification on the rear wing, re: whether the rules meant I was restricted to a "single element" wing, or if a single wing with dual elements was legal.I got a very short response, basically insulting my intelligence for even asking the question. SMH.

Now I look at the new rules, and the car could be setup for ST4, but with "No additional aero mods".Does this mean I cannot run ANY wing or air dam at all, or is the wing and air dam supplied from Pro-Challenge on their standard roadrace car legal?

It would be nice to think I could buy all these expensive parts once, and run the car for many years, without chasing an ever-changing rule set from one year to the next. I just want to have some fun in my retirement, without blowing my whole nest-egg in the first 5 seasons..

David,

Just to be clear, you didn't e-mail the ST Director, because that is me, and I did not e-mail you. You e-mailed your regional ST Leader, and it sounds like you did get the answer that was correct per the rules--sorry if you didn't like how he formatted it. As far as this question, I certainly wouldn't count on other competitors on the forums to interpret the rules for you if you are not sure.

The rule regarding your vehicle in ST4 is as follows:"The following vehicles are approved to use “Production” vehicle status, provided that the frame/chassis, body/aero remain in the original manufactured configuration as specified by the manufacturer (unless designated otherwise below). The “Chassis” Modification Factors and the “Production Vehicle Body” Modification Factors shall not be assessed, but the vehicle specific Modification Factor listed below for each model will apply. None of these vehicles are eligible for the “BTM Aero” Modification Factor. Only the vehicles designated “ST4 approved” may participate in ST4.""Pro Challenge = -0.2 (no additional Aero mods) (ST4 approved)"

So, you must have the body/aero in the original manufactured configuration, with no additional Aero modifications. So, the Pro Challenge Road Racer comes with the wing and air dam, so you can keep them.